Image Sensor Dark Noise Removal via Temperature-Tested Pixel Blocks
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Solution Overview
Problem
Current image sensing devices face challenges in completely removing dark noise components from image data due to differences in dark currents between active and optical black pixels, which affect image quality, especially at varying temperatures.
Innovation Solution
The image sensing device includes test pixel blocks heated to different temperatures to generate pixel signals, allowing for the extraction of pedestal information used to accurately correct noise data and remove dark noise components, with separate blocks for active and optical black pixels to account for temperature and color-specific dark currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If optical black pixels are used to remove dark noise, then dark noise removal is simplified, but incomplete removal occurs due to dark current differences between active and optical black pixels
Solution Approach 1:
The pixel array is divided into multiple test pixel blocks, each containing both active pixels and optical black pixels. This segmentation allows for separate measurement of dark currents in different pixel types, enabling accurate pedestal information extraction that accounts for dark current differences between active and optical black pixels.
Solution Approach 2:
Dark current characteristics are measured in advance under various temperature conditions by heating the test pixel blocks to different temperatures. This preliminary measurement of pedestal information at multiple temperatures enables accurate dark noise removal during actual image capture without requiring real-time complex calculations.
2Device complexity
If single temperature dark current measurement is used, then measurement process is simplified, but noise removal accuracy decreases at varying temperatures
Solution Approach 1:
The system performs preliminary dark current measurements at multiple predetermined temperatures by controlling the heating elements. The measured pedestal information is stored in advance, allowing the image processing unit to select the appropriate temperature-specific pedestal data during image capture, achieving accurate dark noise removal without real-time temperature measurement complexity.
Solution Approach 2:
The patent measures and stores pedestal information at multiple temperature parameters (different heating levels). During operation, the system selects the pedestal information corresponding to the actual temperature condition, effectively adapting to temperature variations without requiring complex real-time temperature sensing and adjustment mechanisms.
3Measurement precision
If multiple test pixel blocks at different temperatures are used, then dark noise removal accuracy is improved, but device structure and power consumption increase
Solution Approach 1:
The pixel array is segmented into multiple test pixel blocks, where each block contains both active pixels and optical black pixels. This segmentation enables simultaneous measurement of dark currents in different pixel types at different temperatures, efficiently capturing the necessary pedestal information for accurate dark noise removal across various operating conditions.
Solution Approach 2:
Each test pixel block serves multiple functions: measuring dark current in active pixels, measuring dark current in optical black pixels, and providing pedestal information for different temperature conditions. This multi-functionality reduces the need for separate measurement systems for each pixel type and temperature condition, thereby limiting the increase in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise removal of dark noise components from image data, improving image quality by using temperature-specific pedestal correction values, thereby enhancing the accuracy of noise reduction across different colors and temperatures.
Implementation Method 1
a heating element disposed in the pixel array and configured to generate heat
Data Source
AI summary
An image sensing device may include a plurality of test pixel blocks and a signal processing unit. The test pixel blocks may be simultaneously heated to different temperatures. The signal processing unit may be in communication with the test blocks and configured to obtain pixel signals for different colors, respectively, based on dark current information associated with the temperatures of the test pixel blocks.